The invention is directed to a method for fabrication of an iron member with a winding for generation of electromagnetic fields.
It is known in the manufacture of electrical machinery to fabricate windings of electrically insulated wires and to place these into grooves of iron members, or however to also utilize the coils in regular operation without such an iron member. For the fabrication of such coils, wires with an essentially circular cross-section are used. For the fabrication of such coils either a device is used as a winding tool, and the thus fabricated coil is then inserted into the iron member, or the iron member is directly wound by placing the wire directly into its grooves. The filling or space factor of such windings or grooves is of the order of magnitude of approximately 65%, meaning, referred to the cross-sectional area of the groove or the winding, 65% of the cross-sections of the wires forming the windings are filled, the rest 35% is essentially air enclosed in the filler regions, which ar bounded by adjacent wires lying next to each other.
It is also known in the construction of electrical machinery (motors, generators, transformers for power supply) to utilize copper wires or copper bands rectangular in cross section. Here we are faced with large copper cross-sections and large winding widths. With wires having rectangular cross-sections there occur great losses of filling factors, and indeed especially at the beginning and end of each winding layer. In copper bands a large winding height is required for applying large winding numbers including insulation, in order to keep the space factor high. With copper wires having a cross-section of less then 1 mm.sup.2 the laying of formed wires is difficult.
The builders of electromachinery attempt continuously to house as much winding copper as possible in a predetermined space, be it a groove or be it a winding space, because the greater the copper cross-section per unit area, the lower is the power loss and the smaller can be the dimensions of the device; also the heat loss can be dissipated so much easier and faster at lower cost, which again lowers the temperature difference between the copper of the winding and the jacket of the device, whereby again the arrangements for cooling the device can be simplified and the device itself can be built to be small because of these reasons, which on the other hand again result in economy of material. Thus, an electric coil of high density and good thermal conductivity is explained in the DE-OS 1789 162 where the winding is placed into a pressing mold and is then pressure-molded to such an extent over its entire surface or at least over a portion of its length, that the individual wires of the winding are deformed. This publication however leaves open how subsequently this winding or coil is to be inserted into the iron core. It is so-to-say only mentioned in passing, that such coils are destined for motors with distinct poles, whose pole shoes can be disassembled in order to insert the winding. In electrical machines with iron members having no distinct or disassemblable poles, it is probably difficult, if not entirely impossible, to utilize such pressure-molded coils.
The DE-PS 33 47 195 shows and describes on the other hand pressure-molded windings in connection with internally grooved iron members (stator and rotor of electrical machinery), wherein expensive auxiliary apparatus is required in order to achieve an adequate space factor in this case. It is indeed observed in the description, that these auxiliary arrangements can be replaced by the "fingers" of the person inserting the coil. This however appears to be a dubious method, since it cannot be determined how the pressure required for pressure molding of such metallic wires can be absorbed by the fingers over a long groove distance.